def test_9():
     root9 = TreeNode(
         20,
         TreeNode(
             10,
             TreeNode(5, TreeNode(3, None, None), TreeNode(7, None, None)),
             TreeNode(15, None, TreeNode(17, None, None))),
         TreeNode(30, None, None))
     return (BinarySearchTree.isBinarySearchTree(root9))
 def test_0():
     root0 = TreeNode(10, TreeNode(5, None, None), TreeNode(15, None, None))
     return (BinarySearchTree.isBinarySearchTree(root0) == True)
 def test_8():
     root8 = TreeNode(0, None, TreeNode(0, None, TreeNode(0, None, None)))
     return (BinarySearchTree.isBinarySearchTree(root8) == False)
 def test_6():
     root6 = TreeNode(8, TreeNode(2, None, None),
                      TreeNode(6, TreeNode(4, None, None), None))
     return (BinarySearchTree.isBinarySearchTree(root6) == False)
 def test_7():
     root7 = TreeNode(0, TreeNode(0, TreeNode(0, None, None), None), None)
     return (BinarySearchTree.isBinarySearchTree(root7) == True)
 def test_5():
     root5 = None
     return (BinarySearchTree.isBinarySearchTree(root5) == True)
 def test_4():
     root4 = TreeNode(10, None, TreeNode(10, None, None))
     return (BinarySearchTree.isBinarySearchTree(root4) == False)
 def test_3():
     root3 = TreeNode(10, TreeNode(10, None, None), None)
     return (BinarySearchTree.isBinarySearchTree(root3) == True)
 def test_2():
     root2 = TreeNode(20, TreeNode(10, None, TreeNode(25, None, None)),
                      TreeNode(30, None, None))
     return (BinarySearchTree.isBinarySearchTree(root2) == False)
 def test_1():
     root1 = TreeNode(20, TreeNode(5, None, None), TreeNode(15, None, None))
     return (BinarySearchTree.isBinarySearchTree(root1) == False)